Aqueous Geochemistry of the Sand‐and‐Gravel Aquifer, Northwest Florida

Katz, Brian G.; Choquette, Anne F.

doi:10.1111/j.1745-6584.1991.tb00496.x

Cited by 12 publications

(7 citation statements)

References 10 publications

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“…The processes that influence the chemical evolution of groundwater in regional-scale groundwater systems have been quantified using modeling techniques for unconsolidated silicate aquifers [e.g., Siegel and Pfannkuch, 1984;Katz and Choquette, 1991] and for carbonate aquifers [e.g., Back and Hanshaw, 1970; Deines et al, 1974;Plumrner, 1977]. In areas where carbonate systems are poorly confined, however, relatively few studies have assessed the changes in the composition of groundwater as it moves downward and reacts chemically with silicate material and recharges the underlying carbonate aquifer.…”

Section: Introductionmentioning

confidence: 99%

Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 2. Chemical Patterns, Mass Transfer Modeling, and Rates of Mass Transfer Reactions

Katz¹,

Plummer²,

Busenberg³

et al. 1995

Water Resources Research

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Chemical patterns along evolutionary groundwater flow paths in silicate and carbonate aquifers were interpreted using solute tracers, carbon and sulfur isotopes, and mass balance reaction modeling for a complex hydrologic system involving groundwater inflow to and outflow from a sinkhole lake in northern Florida. Rates of dominant reactions along defined flow paths were estimated from modeled mass transfer and ages obtained from CFC-modeled recharge dates. Groundwater upgradient from Lake Barco remains oxic as it moves downward, reacting with silicate minerals in a system open to carbon dioxide (CO2), producing only small increases in dissolved species. Beneath and downgradient of Lake Barco the oxic groundwater mixes with lake water leakage in a highly reducing, silicate-carbonate mineral environment. A mixing model, developed for anoxic groundwater downgradient from the lake, accounted for the observed chemical and isotopic composition by combining different proportions of lake water leakage and infiltrating meteoric water. The evolution of major ion chemistry and the •3C isotopic composition of dissolved carbon species in groundwater downgradient from the lake can be explained by the aerobic oxidation of organic matter in the lake, anaerobic microbial oxidation of organic carbon, and incongruent dissolution of smectite minerals to kaolinite. The dominant process for the generation of methane was by the CO2 reduction pathway based on the isotopic composition of hydrogen (•2H(CH4) = -186 to -234%0) and carbon (•13C(CH4) ---65.7 to -72.3%0). Rates of microbial metabolism of organic matter, estimated from the mass transfer reaction models, ranged from 0.0047 to 0.039 mmol L -• yr -• for groundwater downgradient from the lake. 1565 1566 KATZ ET AL.: CHEMICAL EVOLUTION OF GROUNDWATER, 2 adequately tested for sensitivity to uncertainties in hydrochemical data because of the lack of information on environmental isotopes and mineralogy of aquifer material. Furthermore, rates of chemical evolution were not determined because flow paths were poorly defined, the age of groundwater was not estimated, and sources of water were not identified.The Lake Barco study area represents an ideal site to study the hydrochemical interaction between groundwater and lake water leakage and recharge to the UFA. Groundwater flow paths and gradients are relatively stable in the overlying surficial aquifei' and intermediate confining unit [Sacks et al., 1992; Katz et al., this issue]. Recharge to the UFA in this area is representative of hydrologic conditions along upland, highlands, and ridge areas of peninsular Florida [Aucott, 1988].Furthermore, this dilute groundwater system is typical of many poorly confined shallow aquifers whose principal source of recharge is rainfall that reacts with minerals in overlying unconsolidated silicate aquifers [Fritz and Fontes, 1980, 1986]. Groundwater that contains low concentrations of dissolved minerals represents a challenge in assessing material transfer because the concentrations of major ions and ...

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Section: Introductionmentioning

confidence: 99%

Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 2. Chemical Patterns, Mass Transfer Modeling, and Rates of Mass Transfer Reactions

Katz¹,

Plummer²,

Busenberg³

et al. 1995

Water Resources Research

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“…A data base of radium in ground water and drinking water for Escambia County, Florida, was assembled from publicly available information and used as an example. The drinking water supply in Escambia County is predominantly derived from the pumping of the sand-and-gravel aquifer (Katz and Choquette 1991), and total radium activity in the aquifer is naturally close to the MCL, with exceedances reported in several wells and locations within the water supply system. The data set is derived from 407 water samples collected from 137 locations that include municipal supply wells, distribution points, irrigation wells, and monitoring wells in the aquifer.…”

Section: Radium and The Escambia County Data Setmentioning

confidence: 99%

Uncertainty and Trend Analysis—Radium in Ground Water and Drinking Water

Soderberg¹,

Hennet²

2007

Groundwater Monitoring Rem

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Radium activity measurements in water samples are encumbered by relatively large error bars, including for activity values near the regulatory drinking water maximum contaminant level of 5 pCi/L. The large error bars create uncertainty in the evaluation of temporal trends. This uncertainty is often the object of debate and disagreement in regulatory determinations, the design of remedial actions, and/or in litigation. The Mann‐Kendall nonparametric test is perhaps the most commonly used test for trend evaluation in environmental sciences. The test is simple and easy to apply by nonstatisticians and is recommended in several regulations and guidance documents. As typically applied, the Mann‐Kendall test does not consider the uncertainty related to error bars for individual data values. Ignoring this uncertainty can result in misleading conclusions on the presence or absence of trends. In this article, a procedure for trend analysis that accounts for error bars is described. For each data series analyzed, the procedure creates 1000 new data series by randomly assigning values that fall within the error bar around each data point. Trend analysis is then performed on the randomly created data series. The approach is applied to the evaluation of a radium data base containing analytical results from 137 locations (407 water samples) in Escambia County, Florida. The evaluation of the radium data base using the Mann‐Kendall test without accounting for the uncertainty reveals 10 significant trends at the 90% confidence level. Only two of these trends are supported by the data when the uncertainty from analytical error is accounted for.

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“…The study area includes all of Florida, but more detail was given to those areas of principal use of each of the aquifer systems and to the areas where the monitoring wells were located. The sand-and-gravel aquifer of the surficial aquifer system and the Biscayne aquifer have been described in previous publications (Katz and Choquette, 1991;RadellandKatz, 1991).…”

Section: Purpose and Scopementioning

confidence: 99%

“…In areas where the surficial aquifer system is used almost exclusively as a source of water supply and has been extensively studied, surficial aquifers have been individually named. The baseline water quality of these aquifers, the sand-and-gravel aquifer in northwest Florida and the Biscayne aquifer in Broward, Dade, and part of Palm Beach Counties, have been the focus of previous studies by Katz and Choquette (1991) and Radell and Katz (1991), respectively, and will not be discussed in this report.…”

Section: Surficial Aquifer Systemmentioning

confidence: 99%

Hydrochemistry of the surficial and intermediate aquifer systems in Florida

Berndt¹,

Katz²

1992

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Introduction 1 Purpose and scope 2 Previous investigations 2 Methods 3 Surficial aquifer system 4 Hydrogeology 4 Hydrochemistry 6 Intermediate aquifer system 8 Hydrogeology 8 Hydrochemistry 11 Northeastern Florida 12 Panhandle area of Florida 12 Southwestern Florida 12 Factors affecting hydrochemistry of the intermediate aquifer system 14 Downward leakage from the surficial aquifer system 17 Upward leakage from the Upper Floridan aquifer 21 Summary and conclusions 22 References cited 22 Figure 1. Map showing locations of principal counties using water from the surficial aquifer system for public supply and domestic self-supplied use 5 2. Map showing locations of monitoring wells and dominant-ion water types in samples from wells tapping the surficial aquifer system 9 3. Graph showing distribution of dominant-ion water types in the surficial aquifer system and dissolved-solids concentration in groundwater samples as a function of depth of well 10 4. Graphical summary showing concentrations of selected constituents in the surficial aquifer system 11 5. Map showing locations of monitoring wells and dominant-ion water types in samples from wells tapping the intermediate aquifer system in northeastern Florida 12 6. Graphical summary showing concentrations of selected constituents in the intermediate aquifer system in northeastern Florida 13 7. Map showing locations of monitoring wells and dominant-ion water types in samples from wells tapping the intermediate aquifer system in the panhandle area of Florida 13 8. Graphical summary showing concentrations of selected constituents in the intermediate aquifer system in the panhandle area of Florida 14 9. Map showing locations of monitoring wells and dominant-ion water types in samples from wells tapping the intermediate aquifer system in southwestern Florida 15 10. Graphical summary showing concentrations of selected constituents in the intermediate aquifer system in southwestern Florida 16 11. Map showing locations of Areas I and II in southwestern Florida 17 12. Trilinear diagrams showing median-ion composition for water types in the aquifers in Area I 19 Contents III Contents IV

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Aqueous Geochemistry of the Sand‐and‐Gravel Aquifer, Northwest Florida

Cited by 12 publications

References 10 publications

Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 2. Chemical Patterns, Mass Transfer Modeling, and Rates of Mass Transfer Reactions

Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 2. Chemical Patterns, Mass Transfer Modeling, and Rates of Mass Transfer Reactions

Uncertainty and Trend Analysis—Radium in Ground Water and Drinking Water

Hydrochemistry of the surficial and intermediate aquifer systems in Florida

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